After importing svg, [mesh from curve] creates annoying results?
Make sure there are no overlapping segments in your curves before conversion, otherwise remove doubles after conversion to mesh.

Before conversion to mesh make sure your curve is set to 2D and the Fill is set to either just Front or Back, not Both

Also have in mind that converting curves to mesh will always lead do triangulation, and not all curve shapes can be filled entirely by quads, nor without NGons.

Also, if your curve had wholes in them, additional edges will appear, because the mesh structure doesn't support islands. That means there can't be totally disconnected groups of edges sharing the same faces, like in tha building with the whole in the middle.

See this answer for more cleanup techniques